no pressure & where is the water going?

lanceL

Hello to all. This is my second season with steam, which is working pretty well thanks to all the help and knowledge you have shared on this great site. I have the Lost  Art, and some plbg background from my father. Going for efficiency this year I hope!



Two current problems; First:  the system water level drops from 3/4 of the glass to 1/4 (LWC) in 2-4 days, depending on outdoor temps. Second:  The system doesn't build pressure, and then shows a vacuum after shutdown,



Background info; boiler is W-M 400k in, gas, 10 yrs old.  Near piping is insulated & correct, runs quiet, rads don't spit. Building heats pretty well. About 26 rads on 2 floors. Replaced in last year: auto LWCO, thermostat (luxpro, done by service on a no heat call), vaporstat, 0-3# guage, ignition module. Mud leg was cleaned this spring, and boiler was accidentally overfilled and showed no leaks. No chimney vapor evident during firing in cold weather.



So where is the water going?  I found 2 faulty rad vents today, but why the vacuum then? If no pressure built during a 45 min run, is the vaporstat operating at all? Perhaps it is operating on t'stat alone, but is this correct as in Lost  Art, system breathes to fill rads completely? BTW, the whole pigtail tree was rebuilt and is clean. Can all the pressure controls be mounted on one pigtail- it is a cross tee with ptrols on 6" laterals and guages stacked on the riser- and work accurately?  Should it be built on a manifold with multiple p'tails and shorter runs to the device? What is the usual amount of water used in a boiler this size?  I don't want to be adding more than necessary due to the corrosion factor.



A lot of questions, I know.  Maybe the answer will be one simple thing!  Thanks to all and seasons greetings too!



Lance

Steamhead

Do any of your return lines

go underground? If so, they are guilty. 

lanceL

no pressure & where is the water going?

The mud leg lays on the concrete, but shows no water... the wet returns are all suspended.  There is a crawl space with no access that may be the next place to look.

Thanks for your input!

Lance

jpf321

dual pigs

according to Steamhead, an esteemed member who should be revered, pressure control manifold should be on 2 pigtails .. see thread here with pics from Steamhead and "nbc" .. (and disregard my babble) http://www.heatinghelp.com/forum-thread/128365/Looking-for-a-Steam-Pro-for-site-survey-visit#p1181988

lanceL

no pressure & where is the water going?

Thanks for the link!  It seems the issue is one of safety and not accuracy of operation.  I'm afraid I don't remember enough gas law to know if piping makes a pressure difference, but it seems not.  I have realized that I have to clean the pigtail and LWCO probe every spring. Is that often enough, is the question? Thanks,  Lance

jpf321

container size....

the container size (piping) makes no difference in the pressure. PV=nRT .. where V (volume) is always constant in this case.

nicholas bonham-carter

missing water

i presume that you have determined the permanent loss of water by turning off the auto-fill, and if this is not a temporary loss of water, then it must go somewhere.if there were a leak in the crawlspace, then the steam would be apparent there and above.

why not do another overfill-leak test while you are observing the situation, so you can really cross that off the list.

as far as vacuum goes, there is always a vacuum at the end of steaming, but it should be quickly relieved by the vents. an enduring vacuum shows that you need more venting, or that the venting you have is designed for a vacuum system. the vacuum could pull the water up into the returns, for a while showing a plunging waterline in the boiler. unlike the positive steam pressure over which we have some control, a vacuum is always -14.7 psi; and water can be lifted 32 ft. that is the second purpose of vents in the system is to allow the air back in.

remember that the volume of water, represented by the waterline moving from  3/4 to 1/4 is really quite small-maybe only a gallon or so; which you can measure by draining water into a bucket and stopping when the waterline has lowered to 1/4 from 3/4.--nbc

lanceL

no pressure & where is the water going?

Thanks for your reply!  The only autofill on the system is driven by the LWCO; setting the operating level is a manual chore. I haven't busted into the crawlspace yet because it seems so unlikely that there are no signs of steam, but I may have to yet. The mains are vented with Gorton 1-# 1 & 6-# 2 new last year, located at the drip to wet return. I have been thinking of adding 1  #1 to each location.  End of mains now hot after about 7 min from warm. When I cleaned the control tree this year I zero'd the 3# gauge with the boiler cold, and did the blow/ suck test while observing the needle in a mirror-seemed to be ok. First run showed .2psi, but then went neg. and now runs at 0 when steaming and rests at neg the rest of the time!  It holds that neg. set 24/7 !   Should I reset the gauge warm?  Could all the main vents be stuck closed from the overfill if it went that high? They seeem to be working, but I haven't removed any.  Can an overfill test be done safely with the boiler warm- hard to let it go cold this time of year. The water has to be going somewhere. As you said, if it's only a gallon, is that normal usage in a 2-4 day period for 400k boiler? Should I put a second autofill set to the operating level (if possible) and let it go? I think the core problem is the water level change, and the variable pressure is a result, but I sure don't know!

Lance

jpf321

have another look...

nbc, have another look at his post .. I think he implies that it goes from 3/4gauge to 1/4gauge therefore 1/2gauge drop.. not 3/4in to 1/4in (or 1/2in drop) .. gauge units, I would expect to be quite a bit more than a gallon or so.

nicholas bonham-carter

water content

my 1,050,000 peerless has only 3 gallons of water, going from LWCO cutoff point to normal waterline [1/2to1/5] . i think the sections are extremely thin at that point to maximise heat transfer, and that means that you don't have to have a big leak to be at cut-off point. in fact this water in mine was being hidden in a horizontal return pipe just a few inches above the normal waterline. when even very low pressure pressure raised the returns, a few inches, it "hid" the water, but naturally, a few minutes after steaming, it all came back!

now we have the returns dropping straight to the floor, and no longer have that problem.--nbc

jpf321

oh ..

in my basement behemoth .. 1/2 gauge is more like a full bathtub :-) sorry for the alarm.

lanceL

no pressure & where is the water going?

Thanks for all your input.  Yes, I meant 3/4 gauge to 1/4 gauge overall change. The refill time is short at a minimal flow, so I don't think it is a large volume as nbc surmised.  Is this too much water usage considering corrosion?  I looked today, and have another tap at the mid level glass water line where I think I could put another probe as an operating sensor for normal level. I guess I don't know if there is truly a water loss problem or not. If so, I do not want to band aid it by adding water.  ??? Lance

Jamie Hall

Lack of pressure

really isn't a problem, normally -- most steam systems show very little if any pressure until all the radiation is full of steam, then they will go up to cut off rather quickly.  If the boiler is reasonably close to properly sized, this can indeed take the better part of an hour in a system of any size at all.  So simply not seeing a pressure rise -- and not have the vaporstat trip off -- wouldn't bother me.



The loss of water might.  It sounds as though you have one of the newer, smaller boilers, so that it might not be that much water -- but if it seems on the order of a gallon or so every couple of days, that's more than normal and it's leaking somewhere.  A cup or two probably is also a small leak somewhere -- and maybe a perfect bear to find, if it is on a steam line.

lanceL

no pressure & where is the water going?

Thank you all for your help!  I will look further for water leaks, and will let the pressure worry about itself.  Lance

lutorm

Leaky vents?

Have you tested if your Gortons are leaking? My 3rd Gorton is on the way now as the two earlier ones have not sealed properly. The second one was tight enough that at pressures less than 1psi you had to hold a cold wrench to the opening to notice, but over time it seems it leaks enough water to hit the LWCO after ~4days. And it's still tight enough to get a noticeable vacuum on the 0-3 when the burner shuts down.